Validation and calibration of HeadCount, a self-report measure for quantifying heading exposure in soccer players.

The long-term effects of repetitive head impacts due to heading are an area of increasing concern, and exposure must be accurately measured; however, the validity of self-report of cumulative soccer heading is not known. In order to validate HeadCount, a 2-week recall questionnaire, the number of player-reported headers was compared to the number of headers observed by trained raters for a men's and a women's collegiate soccer teams during an entire season of competitive play using Spearman's correlations and intraclass correlation coefficients (ICCs), and calibrated using a generalized estimating equation. The average Spearman's rho was 0.85 for men and 0.79 for women. The average ICC was 0.75 in men and 0.38 in women. The calibration analysis demonstrated that men tend to report heading accurately while women tend to overestimate. HeadCount is a valid instrument for tracking heading behaviour, but may have to be calibrated in women.

Sex Differences Across Concussion Characteristics in US Service Academy Cadets: A CARE Consortium Study.

OBJECTIVE: To describe sex differences in concussion characteristics in US Service Academy cadets. DESIGN: Descriptive epidemiology study. SETTING: Four US service academies. PARTICIPANTS: 2209 cadets (n = 867 females, n = 1342 males). INDEPENDENT VARIABLE: Sex. OUTCOME MEASURES: Injury proportion ratios (IPR) compared the proportion of injuries by sex (females referent) for injury situation, certainty of diagnosis, prolonged recovery, recurrent injuries, mental status alterations, loss of consciousness (LOC), posttraumatic amnesia (PTA), retrograde amnesia (RGA), motor impairments, delayed symptom presentation, and immediate reporting. MAIN RESULTS: Concussions from varsity/intercollegiate sports [IPR of 1.73, 95% confidence interval (CI) 1.43-2.10] and intramurals (IPR of 1.53, 95% CI 1.02-2.32) accounted for a larger proportion in males, whereas concussions outside of sport and military activities accounted for a smaller proportion among males (IPR of 0.70, 95% CI 0.58-0.85). The proportion of concussions with prolonged recovery was lower among males (IPR of 0.69, 95% CI 0.60-0.78), while concussions with altered mental status (IPR of 1.23, 95% CI 1.09-1.38), LOC (IPR of 1.67, 95% CI 1.17-2.37), PTA (IPR of 1.94, 95% CI 1.43-2.62), and RGA (IPR of 2.14, 95% CI 1.38-3.31) accounted for a larger proportion among males. A larger proportion of concussions that were immediately reported was observed in males (IPR of 1.15, 95% CI 1.00-2.31). Proportions of other characteristics (e.g., recurrent injuries) were not different between sexes. CONCLUSIONS: A higher proportion of concussions occurred outside of sport and military training for female cadets, who also displayed proportionally longer recovery times than males, despite males demonstrating a higher proportion of LOC, PTA, and RGA. Possible factors may include different mechanisms of injury outside of sport and military training, different biopsychosocial states associated with sex or injury context, and delayed injury reporting when outside of an observed environment, possibly secondary to perceived stigma about reporting injuries.